SEFI or MFI
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
The Ford MAF (Mass Air Flow) system IS SEFI (SEquential-port Electronic Fuel Injection). The older SD (speed density) is bank fired. However BOTH are MFI (Multi-port Fuel Injection).
THe difference is not in the multi-port designation but in the way the injectors are triggered. With SEquential port Fuel Injection, the injectors are triggered individually much the same way the spark plugs are (albeit a lot less voltage). The older SD (speed density) EFI is still multi-port injection, however the injectors are bank-fired. In other words instead of the system firing each injector individually, it fires the left bank of injectors then the right and back and forth etc. BOTH systems are MFI (Multi-port Fuel Injection). The closest Ford ever came to TBI (Throttle Body Injection) was the ill-fated variable-venturi carburetor which is best melted down so it can be made into something that WORKS. With that failure, the company just skipped the throttle body endeavor and went straight to MFI-type systems.
THe difference is not in the multi-port designation but in the way the injectors are triggered. With SEquential port Fuel Injection, the injectors are triggered individually much the same way the spark plugs are (albeit a lot less voltage). The older SD (speed density) EFI is still multi-port injection, however the injectors are bank-fired. In other words instead of the system firing each injector individually, it fires the left bank of injectors then the right and back and forth etc. BOTH systems are MFI (Multi-port Fuel Injection). The closest Ford ever came to TBI (Throttle Body Injection) was the ill-fated variable-venturi carburetor which is best melted down so it can be made into something that WORKS. With that failure, the company just skipped the throttle body endeavor and went straight to MFI-type systems.
Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
thank you for clearing that up greystreak, however ford did have a throttle body injection, which they called CFI, or Central Fuel Injection. the CFI was not used on any trucks as far as I know though, however it was used for a few years in cars (my capri had CFI).
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carpe_diem
Fuel Injection, Carburetion & Fuel System
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Feb 1, 2004 10:58 PM
